Pound Per Square Foot (psf)

US & ImperialTraditional unit (still used in some regions)

About 47.88 pascals. Used in US structural engineering for distributed loads.

1 pound per square foot = 47.88025898 pascals (approximately).

About the pound per square foot

A square foot is 144 square inches, so one pound per square foot is one 144th of a psi, which comes to about 47.88 Pa; NIST gives 47.88026. The number is easy to picture: spread one pound-force evenly over a floor tile a foot across and that is the pressure, tiny compared with the 101,325 Pa of one standard atmosphere.

Building codes in the United States commonly state loads on floors and roofs this way, and snow and wind pressures are tabulated in the same unit. Metric countries use kilopascals or newtons per square metre instead, and 1 kPa is about 20.9 psf. Multiplying a psf figure by 144 gives psi, and by 47.88 gives pascals, so a 40 psf floor load is about 1.9 kPa.

Sources: NIST SP 811, Appendix B.8; Wikipedia: Pounds per square inch

Pound Per Square Foot conversion chart

1 pound per square foot expressed in every other pressure unit:

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• pound per square inch (pressure)
• kilopound per square inch (pressure)
• inch of mercury (pressure)
• inch of water (pressure)
• inch (length)
• foot (length)
• yard (length)
• mile (length)
• thou (length)
• league (length)
• furlong (length)
• chain (length)
• rod (length)
• link (length)
• hand (length)
• pound (weight & mass)

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